As α1,2-fucosyltransferase genes, animal-derived genes [Proc. Natl. Acad. Sci. USA, 87, 6674 (1990); Immunogenetics, 44, 76 (1996); J. Biol. Chem., 270, 8844 (1995); J. Biol. Chem., 270, 4640 (1995); J. Biol. Chem., 271, 16975 (1996)] have been obtained. However, there is no example in which an animal-derived α1,2-fucosyltransferase gene was expressed as an active protein using a microorganism such as Escherichia coli. On the other hand, in the case of microorganisms, it is reported that an α1,2-fucosyltransferase gene has been obtained from Helicobacter pylori [Mol. Microbiol., 31, 1265 (1999)], and expressed in Escherichia coli, however, its enzyme activity was extremely weak even under the control of a strong promoter [Microbioogy, 145, 3245 (1999)]. It is reported that Helicobacter pylori-derived α1,2-fucosyltransferase gene in which the nucleotide sequence was modified was expressed in Escherichia coli as a host (W01/46400), however, an α1,2-fucosyltransferase having higher activity is desired to be developed.
Among fucose-containing complex carbohydrates, there are fucose-containing complex carbohydrates which are known as blood group antigens, and it has been recently clarified that those complex carbohydrates undergo structural changes with canceration of cells. [Anal. Biochem., 251, 89 (1997)], and fucose-containing complex carbohydrates of this type is expected to be developed as a tumor marker and as a pharmaceutical preparation. Human milk is abundant in oligosaccharides, and fucose-containing complex carbohydrates (2′-fucosyllactose is one of the main component) account for 70% of the total oligosaccharides [Glycobiology, 8, 615 (1988)]. Since it is known that a complex carbohydrate having a Fucα1-2Gal structure which is also contained in oligosaccharides in human milk inhibits infection of Candida albicans [Infect. Immun., 59, 1650(1991)], the fucose-containing complex carbohydrate is considered as a strong candidate for a safe preventive agent for infection.
As the production of fucose-containing complex carbohydrates such as 2′-fucosyllactose, an extraction method from human milk [J. Chromatogr., 211, 170 (1981)], a production process using a transgenic animal [J. Biol. Chem., 270, 29515 (1995); U.S. Pat. No. 5,700,671], a production process using an enzyme (U.S. Pat. No. 5,583,042) and a production process using a microorganism (WO01/46400) have been reported, but each of them has problems from the viewpoints of cost and productivity so that a process for efficiently producing fucose-containing complex carbohydrate has been desired.